Cosmetics companies are particularly interested in formulating treatment cosmetics which exert beneficial effects on skin and hair. Since it is known that various animal derived substances provide beneficial effects to skin and hair, it has become popular to incorporate these substances into cosmetics and personal care products. For example, animal collagen is known to have moisturizing and film forming properties, and is a popular additive to treatment cosmetics. Animal collagen protein is the main component of connective tissues, skin, muscles and tendons. It is a fibrous protein of about 100,000 molecular weight, rich in proline and hydroxyproline, and structurally analogous to a three-stranded rope in which each strand is a polypeptide chain. Collagen is responsible for most of skin structure. In the course of aging the polypeptide chains of collagen polymerize The result is "cross linking", which causes wrinkling of the skin as well as reduction in skin elasticity.
Other non-collagen animal proteins such as plasma proteins, placental proteins, or proteins from milk sources are also popular as cosmetics additives, as well as proteins from lower animals such as silkworm, fish, bacteria, yeast, or non-specified marine sources.
Extensins are a family of plant derived hydroxyproline rich glycoproteins (HRGP) firmly bound to the primary cell wall of several species of monocotyledonous and dicotyledenous plants. Extensins are also rich in serine, valine, tyrosine, lysine, and in some instances threonine, and the polypeptide backbone comprises repeating hydroxyproline units in conjunction with other basic amino acids such as valine, lysine, proline, tyrosine, histidine, serine, and threonine. The hydroxyproline component is heavily glycosylated. Extensins play a role in growth, regulation, stress response, cell-cell recognition, and reproductive physiology of plants. The protein is widely distributed throughout the plant kingdom. Extensins are generally insoluble in muro because of their extensive cross linking, so the intact protein has not been isolated from mature plants, which has made the scientific study of intact extensin protein much more difficult. A hydrolyzed form of extensin is available commercially through Centerchem, Stamford, Conn. However, this hydrolyzed product contains very small polypeptide chains having molecular weights of 100-1500 daltons. The term "hydrolyzed" means that the protein has been denatured, possibly fragmented, and the tertiary structure destroyed. It is important to understand that the tertiary structure of a protein is intimately involved with the proper biochemical functioning of that protein.
The estimated size of intact extensin protein is greater than 100,000 daltons, or about 100,000-150,000 daltons. The term "intact" means that the protein is not hydrolyzed or denatured, but still retains its tertiary structure.
It is known that prior to incorporation of insoluble cross linked extensin into the plant cell wall it exists in a soluble form which can be isolated by salt extraction of cell suspension cultures containing the soluble precursor form.
It has unexpectedly been discovered that this soluble form of extensin may be incorporated into cosmetics as an analog for animal collagen and will act to smooth, tighten, and enhance skin texture. Extensins also contain large amounts of humectant sugars which are capable of binding water, thus making them ideal humectants.